Interactions between dietary fat type and exogenous enzyme supplementationof broiler diets based on maize, wheat, triticale or barley

Four growth experiments and a balance study were carried out to examine the effects of different fat types (beef tallow or soyabean oil) in broiler di ets based on wheat, triticale, maize or barley in response to feed enzyme s upplementation. Performance parameters were recorded over 35 days. Viscosit y in the ileal digesta, apparent digestibility of fat and protein at the te rminal ileum were measured at day 21 of age. In addition, fat digestibility was measured at the faecal level along with apparent metabolizable energy value (AME(N)) and apparent net protein utilization (NPUa). It was found that enzyme addition to all diets improved feed to gain ratio significantly. This was most visible in triticale- and barley-based diets s upplemented with tallow than in the soyabean oil-containing counterparts un til 21 days of age. Effects became smaller or disappeared when the whole fa ttening period was considered. Significantly better performance of broilers fed soyabean oil compared with tallow-containing diets was observed over t he whole fattening period. Intestinal viscosity was significantly reduced by enzyme addition to all di ets. Furthermore, significantly higher intestinal viscosity was found in ta llow-fed birds (triticale-, barley- or maize-based diets). Apparent protein digestibility at the terminal ileum was not affected by fat type but was i mproved by enzyme supplementation in wheat- and barley-based diets. Fat dig estibility at both the ileal and faecal levels was significantly higher in birds fed the soyabean oil-containing diets and was significantly improved after enzyme supplementation. The enzyme effect on fat digestibility was mo re pronounced at the faecal level and was positively correlated to AME(N) a nd NPUa.